This invention relates to an improved micro tunnelling head and method of horizontal earth boring utilizing an improved cutting head drive combined with apparatus for removing cuttings with provisions for improved steering of an articulated housing carrying the cutting head for rotation.
Micro tunnelling heads in present use commonly utilize a centrally disposed power take off drive for the cutting head together with a separate belt conveyor or separate auger conveyor receiving cuttings at the bottom of an enlarged chamber receiving cuttings from the cutting head. Such apparatus is complicated and expensive. Furthermore, boring apparatus constructed in this fashion results in a compartment for workers accessing the head. Horizontal earth boring machines of this type are include those manufactured by American Augers, Inc. of Wooster, Ohio. Another supplier of tunnelling equipment, Neil H. Akkerman, utilizes a ring gear drive for the cutting head together with a separate conveyor for removing cuttings. Such apparatus constructed in accordance with the prior art is not only complicated and expensive but also is extremely difficult to steer because of the fact that the steering apparatus provides articulation at a substantial distance rearwardly of the cutting head.
An earth boring apparatus with a steering head is illustrated in U.S. Pat. No. 4,977,967 having a housing which is hingedly attached to a casing, the housing being positioned immediately behind the cutting head. Steering adjustments are made by manipulating a tube which also supplies lubricant such as driller's mud to the cutting head. A disadvantage of such apparatus resides in the fact that the auger which is centrally disposed and drives the cutting head is coextensive with the casing so as to limit the length of the drive and spoil delivery system.
A drive employing a hex connection is illustrated in U.S. Pat. No. 4,632,195, but is not adapted to articulation as is the drive effected by the hex connection to the auger shaft of the present invention.
Also note the difference to U.S. Pat. Nos. 4,630,967; 4,684,290; and 4,763,954.